How to find the Set - Subset of two files from the command line?

bash, linux, set, unix, zsh

Solution

This will suppress common lines:

comm -3 a b

Problem

I have two files with sorted lines. One file (B) is a subset of the other file (A). I would like to find all lines in A that ARE NOT in B. Ideally, I would like to create a file (C) that contains these lines. Is this possible in Unix? I'm looking for a one line command to do this instead of writing a script. I looked at the `join` and `diff` commands, but I could not find a command option to do this. Thanks for the help.

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